This invention relates generally to a system for heating the service cabin of a machine operated by an internal combustion engine, wherein heated oil is fed by a high-pressure supply pump from the engine oil sump through an oil conduit and returned to the oil sump, a pressure-reducing element in the conduit for elevating the temperature of the oil flowing therethrough, a line by-passing the element and having a flow control valve therein, a heat exchanger in the conduit downstream of the element and located in the service cabin for heating the area thereof.
In a known arrangement of this general type, both the high-pressure supply pump and the pressure-reducing element are located outside the internal combustion engine and are connected via external lines with the interior of the engine. These external lines, carrying heating medium under high-pressure, are particularly susceptible to rupture and leakage, and because of their external course, present a safety hazard and possible damage to the surroundings outside the engine.